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The card will treat a data block as successfully received and ready for programming only if the CRC data of the

block was validated and the CRC status token sent back to the host. Figure 4-23 is an example of an interrupted (by

a host stop command) attempt to transmit the CRC status block. The sequence is identical to all other stop

transmission examples. The end bit of the host command is followed, on the data line, with one more data bit, end

bit and two Z clock for switching the bus direction. The received data block, in this case is considered incomplete

and will not be programmed.

<---- Host Command ----> < N

Cycles > <----- Card response-----> <Host Cmnd>

CMD S T content CRC E Z Z P P * * * * * * P S T content CRC E S T Content

--Data block-> CRC Status

Å------------Card is programming ----------Æ

DAT D D D D D Z Z S Status E Z Z S L * * * * * * ** * * * * * * * * * * * * E Z Z Z Z Z Z Z Z

1) The host interrupted the card’s CRC status response.

Figure 4-23. Stop Transmission During CRC Status Transfer from the Card

All previous examples dealt with the scenario of the host stopping the data transmission during an active data

transfer. The following two diagrams describe a scenario of receiving the stop transmission between data blocks. In

the first example the card is busy programming the last block while in the second the card is idle. However, there

are still un-programmed data blocks in the input buffers. These blocks are being programmed as soon as the stop

transmission command is received and the card activates the busy signal.

<---- Host Command ----> < N

Cycles > <----- Card response-----> <Host Cmnd>

CMD S T content CRC E Z Z P * * * P S T content CRC E S T Content

<---------- Card is programming ---------->

DAT S L * * * * * * * * * * * * * * * * * * * * * * * ** ** * * * * * * * * * L E Z Z Z Z Z Z Z Z

Figure 4-24. Stop Transmission Received After Last Data Block. Card is Busy Programming

<---- Host Command ----> < N

Cycles > <----- Card response-----> <Host Cmnd>

CMD S T content CRC E Z Z P * * * P S T content CRC E S T Content

<---------- Card is programming ---------->

DAT Z Z Z Z Z Z Z Z Z Z Z S L * ************************* * L E Z Z Z Z Z Z Z Z

Figure 4-25. Stop Transmission Received After Last Data Block. Card becomes Busy

Erase, Set and Clear Write Protect Timing

The host must first tag the start (CMD32) and end (CMD33) addresses of the range to be erased. The erase

command (CMD38), once issued, will erase all the selected write blocks. Similarly, set and clear write protect

commands start a programming operation as well. The card will signal “busy” (by pulling the DAT line low) for the

duration of the erase or programming operation. The bus transaction timings are the same as given for stop tran

command in Figure 4-24.

Reselecting a Busy Card

When a busy card, which is currently in the dis state, is reselected it will reinstate its busy signaling on the data line.

The timing diagram for this command/response/busy transaction is the same as given for stop tran command in

Figure 4-25.

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SanDisk SD032 Handbuch Seite 83